Lattice enthalpies of lanthanide orthoferrites LnFeO3

Abstract

Lattice enthalpies Δ L H θ of lanthanide orthoferrites, LnFeO 3 have been determined by the Born-Haber cycle and compared with those calculated by an empirical equation. Enthalpies of formation of LnFeO 3 from two different sources have been employed: from oxides (Ln 2 O 3 , Fe 2 O 3 ), for 12 LnFeO 3 , and from elements, for 8 LnFeO 3 , but the differences in Δ L H θ are very small. The Born-Haber cycle in both routes results in close values of Δ L H θ to those obtained by the empirical equation of Glasser and Jenkins. A correspondence in dimension and magnitude has been found between the partial derivative of the lattice enthalpies to the molar volumes and an upper limit of the shear moduli of the lanthanide orthoferrites.